An Ultralow Power Mixed Dimensional Heterojunction Transistor Based on the Charge Plasma pn Junction.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Reliable doping of 2D materials is crucial for next-generation microelectronics, especially hole doping for transition metal dichalcogenides (TMDCs).
• Most TMDCs are inherently electron-doped due to sulfur vacancies, hindering their application in silicon-based electronics.
• The development of sub-10 nm channel length devices requires advanced doping strategies to sustain Moore's Law.

Purpose of the Study:

• To develop a reliable hole doping method for tungsten disulfide (WS2), a key 2D material.
• To demonstrate the fabrication of ultralow-power transistors and diodes using this doping technique.
• To investigate the performance of WS2-based devices formed via a charge plasma pn heterojunction.

Main Methods:

• Hole doping of WS2 was achieved using a silicon substrate as the dopant medium.
• Fabrication of ultralow-power current sourcing transistors and gated WS2 pn diodes.
• Formation of a charge plasma pn heterojunction between WS2 thin-film and heavily doped bulk silicon.

Main Results:

• Achieved ultralow switchable output current down to 0.01 nA µm⁻¹ and an off-state current of approximately 1 × 10⁻¹⁴ A µm⁻¹.
• Demonstrated static power consumption in the range of 1 fW µm⁻¹ to 1 pW µm⁻¹.
• Obtained an output current ratio of 10³ at a 0.1 V supply voltage, with stable output current (<3% variation) regardless of gate voltage.

Conclusions:

• The developed method provides a reliable approach for hole doping of WS2, addressing a critical need in 2D material research.
• The charge plasma heterojunction enables the creation of highly efficient, ultralow-power electronic devices.
• This work paves the way for the integration of 2D materials into future microelectronic circuits, potentially replacing silicon in advanced applications.